WO2008050581A1

WO2008050581A1 - Rotation angle detector

Info

Publication number: WO2008050581A1
Application number: PCT/JP2007/069086
Authority: WO
Inventors: Fumihiko Abe; Kengo Tanaka; Dongzhi Jin
Original assignee: The Furukawa Electric Co., Ltd.
Priority date: 2006-10-26
Filing date: 2007-09-28
Publication date: 2008-05-02
Also published as: EP2088397A4; JPWO2008050581A1; EP2088397A1; US20100315074A1

Abstract

A rotation angle detector (100) in which a magnetic sensor (120) is placed so as to measure the magnetic flux density in the direction of the rotation axis of a magnet (110). The magnet (110) is chamfered at its portion near the magnetic sensor (120) and this moderates the radial gradient of the magnetic flux at the position of the magnetic sensor (120). As a result, even if the magnet (110) radially moves due to radial play, a variation in the magnetic flux density at the position of the magnetic sensor (120) is less.

Description

Specification

Rotation angle detector

Technical field

The present invention relates to a rotation angle detection device that detects a rotation angle by arranging a magnetic sensor in a non-contact manner with respect to a rotating body.

Background art

Conventionally, as a rotation angle detection device for detecting the rotation angle of a rotating body, N-pole and S-pole magnets constituting a magnetic circuit are fixed so as to rotate integrally with the rotating body, and the magnet's magnetic There are many known sensors configured to detect the angle at which the rotating body rotates with respect to the magnetic sensor by arranging a magnetic sensor for detecting the strength in the vicinity of the magnet. It is used in various fields such as DC motors. Hall elements are generally known as magnetic sensors used in rotation angle detection devices!

[0003] As a conventional example of a rotation angle detection device, for example, there is one described in Patent Document 1. FIG. 10 shows a rotation angle detection device disclosed in Patent Document 1. In FIG. The rotation angle detection device 900 shown in the figure is configured such that a disc-shaped magnet 901 is supported by a rotation shaft 904 and can be rotated around the rotation shaft 904 in the direction indicated by the white arrow. Has been.

[0004] The magnetic sensors 902 and 903 are both Hall elements having the same temperature characteristics, and an angle formed by a straight line connecting the magnetic sensor 902 and the center O of the disk and a straight line connecting the magnetic sensor 903 and the center O is formed. It is arranged to be approximately 90 degrees. Further, the magnetic sensors 902 and 903 are arranged immediately below the outer periphery of the magnet 900.

[0005] The rotation angle detection device 900 described in Patent Document 1 configured as described above provides a rotation angle detection device in which the size of the entire sensor can be made smaller than before and the performance is stable. I will be able to do it.

Patent Document 1: Japanese Patent Laid-Open No. 2003-75108

Disclosure of the invention

Problems to be solved by the invention

[0006] However, the conventional rotation angle detection device has the following problems. Measurement The target rotating body has an axial backlash in which the rotating shaft moves slightly in the radial direction, and the magnet fixed to the rotating body by the axial backlash slightly changes in the radial direction relative to the magnetic sensor. Resulting in. The magnetic sensor is disposed close to any location around the outer periphery of the magnet, and in Patent Document 1, it is disposed immediately below the outer periphery.

[0007] Since the outer circumferential surface of the magnet is formed at right angles to the upper and lower surfaces of the rotating body, the magnetic flux density of the magnet changes sharply at the boundary portion between the outer circumferential surface and the upper and lower surfaces, that is, at the corners. Forming. For this reason, when the magnet shifts in the radial direction with respect to the magnetic sensor, the measured value of the magnetic flux density measured by the magnetic sensor also fluctuates greatly, which increases the measurement error of the rotation angle. there were.

[0008] In order to minimize the measurement error of the rotation angle as described above, the force S, which has been conventionally taken to suppress the backlash of the rotary shaft as much as possible, is completely reduced in the radial play of the rotary shaft. It cannot be lost. As described above, since the magnetic flux density changes sharply at the corners of the magnet, even if the radial play is reduced, the influence on the magnetic flux density is large, and the measurement error of the rotation angle can be sufficiently reduced. There wasn't.

[0009] Therefore, the present invention has been made to solve these problems, and an object of the present invention is to provide a rotation angle detection device that can suppress an error in the rotation angle due to the axial backlash of the radial direction.

Means for solving the problem

[0010] The first aspect of the rotation angle detection device of the present invention has at least an upper surface, a lower surface, and an outer peripheral surface, a magnet fixed to the detected rotating body and rotating integrally, and an upper surface or a lower surface of the magnet. A magnetic detector that is arranged in the vicinity of the outer peripheral corner formed by the outer peripheral surface and detects the magnetic strength of the magnet, and calculates the rotation angle of the detected rotating body from the output of the magnetic detector A rotation angle detection device comprising an arithmetic processing unit,

A partial force formed by removing a part of the outer peripheral corner portion over the entire circumference forms a communication surface that connects the upper surface or the lower surface and the outer peripheral surface, and the magnetic detector is disposed in proximity to the communication surface. ! /

[0011] In another aspect of the rotation angle detection device of the present invention, the outer peripheral surface is parallel to the rotation axis of the magnet, the outer peripheral surface is substantially perpendicular to the upper surface and the lower surface, and the rotation shaft of the magnet is Through In the cross section, the outer peripheral line corresponding to the outer peripheral surface and the upper and lower lines corresponding to the upper and lower surfaces are substantially vertical, and the connecting line corresponding to the connecting surface connects the outer peripheral line and the upper or lower surface line. And! /, Characterized by.

[0012] Another aspect of the rotation angle detection device of the present invention is characterized in that the connecting surface is a flat surface, a curved surface, or a multistage surface.

[0013] In another aspect of the rotation angle detection device of the present invention, the detection surface faces the communication surface and is arranged perpendicular to the rotation axis, and detects the magnetic strength of the magnet in the rotation axis direction. It is characterized by this.

[0014] In another aspect of the rotation angle detection device of the present invention, the rotation shaft side end of the detection surface of the magnetic detector is between one end and the other end of the communication surface. It is arranged so that it is located! /.

In another aspect of the rotation angle detection device of the present invention, the outer peripheral corner portion is removed with respect to a rectangular area formed by an outer peripheral line, an upper surface line, and a lower surface line of a cross section of the magnet passing through the rotation axis. The ratio of the part of the area is 5% or more and 35% or less.

In another aspect of the rotation angle detection device of the present invention, the outer peripheral angle portion is removed with respect to a rectangular area formed by an outer peripheral line, an upper surface line, and a lower surface line of the magnet passing through the rotation axis. Part of the area is 20% or more and 30% or less.

[0017] In another aspect of the rotation angle detection device of the present invention, the magnet is a magnet whose at least outer periphery is substantially circular, and whose magnetic strength varies along the circumferential direction of the previous magnet. It is characterized by that.

The invention's effect

[0018] According to the rotation angle detection device of the present invention, the chamfered corners close to the magnetic sensor of the magnet that is fixed to the rotation body to be detected and rotates integrally with each other can be rattled in the radial direction of the rotation body. Even if it occurs, the rotation angle can be measured with high accuracy.

Brief Description of Drawings

FIG. 1 is a block diagram showing a configuration of a rotation angle detection device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a magnetic sensor using a Hall element. FIG. 3] A graph showing the change in magnetic flux density formed by the magnet and the magnetic flux density due to the radial movement of the magnet.

FIG. 4 is a block diagram showing a configuration of a rotation angle detection device according to a second embodiment of the present invention.

FIG. 5] A diagram showing the relationship between the rotation angle of the magnet and the output of the magnetic sensor.

[Fig. 6] A diagram showing the relationship between the radial movement distance of the magnet and the magnetic flux density for each chamfer size. Show.

FIG. 7 is a graph showing the relationship between the size of the removal area of the chamfered portion, the rotation angle error of the magnetic sensor, and the magnetic flux density. 8] The relationship between the size of the removal area and the amplification factor and angle error of the amplifier.

FIG. 9 is a block diagram showing a configuration of a rotation angle detection device according to a third embodiment of the present invention.

[10] FIG. 10 is a block diagram showing a configuration of a conventional rotation angle detection device.

Explanation of symbols

100, 200, 300, 900 Rotation angle detector

110, 310, 901, 910 magnets

111, 311 Outer surface

112 Top view

113 Bottom

114, 314 Chamfer (contact surface)

120, 220, 902, 903, 911 Magnetic sensor

121 Hall element

122

123 amplifier

131, 132 magnetic field lines

240, 315 Cross section

904 Rotation axis BEST MODE FOR CARRYING OUT THE INVENTION

[0021] A rotation angle detection device according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. Note that components having the same functions are denoted by the same reference numerals for simplification of illustration and explanation.

[0022] A rotation angle detection apparatus according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a structural diagram showing a rotation angle detection device 100 of the present embodiment, where (a) is a plan view in a direction perpendicular to the rotation axis, and (b) is a cross-sectional view as viewed in a plane passing through the rotation axis. Are shown respectively. The rotation angle detection device 100 includes a columnar magnet 110 fixed to a rotating body (not shown), and a magnetic sensor 120 fixed in a non-contact manner directly under the outer peripheral surface 111 of the magnet 110.

The magnet 110 is magnetized in the radial direction, and one of the radial directions is an N pole and the other is an S pole. It is necessary to secure a certain thickness of the magnet so that a magnetic field intensity sufficient to measure the change in magnetic flux density due to the rotation of the magnet 110 can be obtained by the magnetic sensor 120. For example, it can be set to about 3 mm. In FIG. 1, the force S where the position of the magnetic sensor 120 is directly below the outer peripheral surface 111 of the magnet 110 is not limited to this. For example, the magnetic sensor 120 may be disposed immediately above the outer peripheral surface 111.

As the magnetic sensor 120, for example, a Hall element can be used. A Hall element is a magnetic sensor that uses the Hall effect of a semiconductor and can directly convert magnetism into electricity. As shown in FIG. 2, when a magnetic field is applied to the Hall element 121 with a constant current 122 flowing through the Hall element 121, a Hall voltage is generated at the Hall terminal 121. The output of the magnetic sensor 120 is obtained by amplifying this with the amplifier 123.

The cylindrical magnet 110 includes an upper surface 112, a lower surface 113, and an outer peripheral surface 111 in a three-dimensional manner, and a part of the outer peripheral corner formed by the upper surface 112 or the lower surface 113 and the outer peripheral surface 111 is the entire periphery. The partial force formed by being removed is formed as a connecting surface 114 that connects the upper surface 112 or the lower surface 113 and the outer peripheral surface 111.

The outer peripheral surface 111 is parallel to the rotation axis of the magnet, and the outer peripheral surface 111, the upper surface 112, and the lower surface 113 are substantially perpendicular. In plan view, as shown in FIG. 1 (b), in the cross section passing through the rotation axis of the magnet, the outer peripheral line 111 corresponding to the outer peripheral surface 111 and the upper surface lines corresponding to the upper surface 112 and the lower surface 113. 112 and the lower surface line 113 are substantially vertical, and a connection line 114 corresponding to the connection surface connects the outer peripheral line 111 and the upper surface line 112 or the lower surface line 113. In the following, the outer peripheral surface or outer peripheral line is indicated by 111, the upper or upper surface line is indicated by 112, and the lower or lower surface line is indicated by 113.

That is, as shown in FIG. 1 (b), the rotation angle detection device 100 of the present embodiment has a chamfered portion (a chamfered portion obtained by cutting away the outer peripheral corner portion formed by the outer peripheral surface 111 and the lower surface 113 of the magnet 110). That is, it is characterized in that a communication surface 114 is formed. In this embodiment, since the magnetic sensor 120 is arranged on the lower surface 113 side, the chamfered portion 114 is formed at the outer peripheral corner formed by the outer peripheral surface 111 and the lower surface 113. When the magnetic sensor 120 is disposed on the upper surface 112 side, the chamfered portion 114 is formed at the outer peripheral corner formed by the outer peripheral surface 111 and the upper surface 112.

In the present embodiment, the magnetic sensor 120 is arranged to measure the magnetic flux density in the rotation axis direction of the magnet 110. Further, the detection surface 120a of the magnetic sensor 120 is arranged so that a part thereof is directly below the chamfered portion 114 and the remaining part is outside the outer peripheral surface 111. The radial position of the magnetic sensor 120 is such that the end 120b of the detection surface 120a on the rotating shaft side is outside the intersection of the chamfered portion (connecting surface) 114 and the bottom surface 113 and inside the outer peripheral surface 111. It is better to decide. That is, it is preferable to determine the radial position of the magnetic sensor 120 so that at least the end 120b on the rotation axis side of the detection surface 120a is positioned immediately below the chamfered portion 114.

The shape of the chamfered portion 114 shown in FIG. 1 is a C-chamfer with a flat cut surface, but is not limited to this. For example, a curved R-chamfer may be used. It is also possible to do this. The size of the chamfered portion 114 can be appropriately selected within a predetermined range as will be described later. In any case, it is preferable that the magnetic sensor 120 is determined so that the magnetic flux density in the rotation axis direction of the magnet 110 can be suitably measured.

As described above, by chamfering the corner of the magnet 110 at a position close to the magnetic sensor 120, the radial gradient of the magnetic flux density at the position of the magnetic sensor 120 can be made gentle. That is, even if the magnet 110 moves in the radial direction due to the radial play, the change in the magnetic flux density at the position of the magnetic sensor 120 can be reduced.

FIG. 3 (a) is a diagram schematically showing the magnetic flux density formed by the magnet 110. Fig 3 In (a), the magnetic lines 131 shown by solid lines indicate those formed by the magnet 110 having the chamfered portion 114 of the present embodiment, and the magnetic lines 132 shown by broken lines do not have a chamfered portion. It is formed with a cylindrical magnet. At the position of the magnetic sensor 120, the spacing force of the magnetic force lines 131 formed by the magnet 110 having the chamfered portion 114 is larger than the spacing of the magnetic force lines 132 formed by the conventional magnet having no chamfered portion. This shows that the formation of the handle 114 makes the change in the radial direction of the magnetic flux density at the position of the magnetic sensor 120 moderate.

[0031] FIGS. 3B and 3C show how the magnetic flux density force S in the rotation axis direction at the position of the magnetic sensor 120 and the radial play of the magnet 110 change. FIG. 3 (b) shows a case of a magnet 910 having no conventional chamfered portion, and FIG. 3 (c) shows a case of the magnet 110 of this embodiment.

In the case of the conventional magnet 910 shown in FIG. 3B, the magnetic flux density at the position of the magnetic sensor 911 rapidly changes when the magnet 910 moves in the radial direction. On the other hand, in the case of the magnet 110 of the present embodiment, the change in the magnetic flux density at the position of the magnetic sensor 120 is greatly reduced by forming the chamfered portion 114. This indicates that by forming the chamfered portion 1 14, the magnet 110 can be formed so that the magnetic flux density gradually changes in the radial direction.

Yes

[0033] As described above, in the rotation angle detection device 100 of the present embodiment, the force S that makes the magnetic flux density measured by the magnetic sensor 120 change significantly due to the backlash in the radial direction of the magnet 110 is smaller than the conventional force S. It becomes possible. As a result, even when the magnet 110 rotates with radial play, it is possible to reduce the measurement error of the rotation angle and increase the accuracy.

[0034] A rotation angle detection apparatus according to a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a structural diagram showing the rotation angle detection device 200 of the present embodiment, where (a) is a plan view in a direction perpendicular to the rotation axis, and (b) is a cross-sectional view as viewed in a plane passing through the rotation axis. Are shown respectively. In the present embodiment, another magnetic sensor 220 is added in addition to the magnetic sensor 120.

[0035] The rotation angle detection device 200 of the present embodiment is configured to further increase the measurement accuracy of the rotation angle by using two magnetic sensors 120 and 220 as magnetic sensors. The magnetic sensor 220 is arranged in a direction rotated by 90 ° in the circumferential direction with respect to the magnetic sensor 120. The rotational axis direction and radial direction are the same as those of the magnetic sensor 120. Therefore, the relative positional relationship between the magnetic sensor 220 and the chamfered portion 114 is the same as that of the magnetic sensor 120, and the change in magnetic flux density at the magnetic sensor 220 position due to the backlash in the radial direction of the magnet 110 is also Similar to the magnetic sensor 120, it becomes gentle.

The magnet 110 is magnetized in the radial direction, and the distribution of the magnetic flux density in the circumferential direction is configured to be approximately a sine wave. Also, since the arrangement of the magnetic sensor 220 and the magnetic sensor 120 is shifted by 90 ° in the circumferential direction, the output of the magnetic sensor 220 = sin Θ and the output of the magnetic sensor 120 = cos Θ (Θ: rotation angle) You can see.

[0037] Therefore, in the rotation angle detection device 200, by using the two magnetic sensors 120 and 220, the rotation angle range of 360 degrees can be further accurately determined by using the angle = arctan (output of the magnetic sensor 220 / output of the magnetic sensor 120. ), And an example of the measurement results will be described below. In the following, a magnet 910 having a rectangular cross section shown in FIG. 3B is used as a conventional magnet for comparison.

The relationship between the output of the magnetic sensor 120 (or 220) and the rotation angle of the magnet 110 is shown in FIG. In the figure, a solid line 231 shows the relationship between the rotation angle of the magnet 110 and the output of the magnetic sensor 120 when the magnet 110 rotates without backlash in the radial direction. In this case, as the magnet 110 rotates from 0 degree to 180 degrees, the output of the magnetic sensor 120 changes from 0V to 2V.

[0039] On the other hand, when the conventional magnet 910 having no chamfered portion rotates with backlash in the radial direction, the output of the magnetic sensor 911 when the rotation angle is 0 degrees as shown by the broken line 232 is On the other hand, it becomes smaller than the solid line 231. On the other hand, when it is 180 degrees, it becomes larger and does not become 0V. As described above, in the conventional magnet 910 having no chamfered portion, the output 232 of the magnetic sensor 911 greatly changes because the output of the magnetic sensor 911 changes greatly only by a slight deviation in the radial direction due to the radial play. A relatively large deviation from the solid line 231 without the. For this reason, if the rotation angle is determined with reference to the solid line 231 without backlash, the error of the rotation angle becomes large.

Furthermore, when the magnet 110 of the present embodiment having the chamfered portion 114 rotates with backlash in the radial direction, the output of the magnetic sensor 120 changes as indicated by a one-dot chain line 233. One-dot chain line 233 almost overlaps the solid line 231 and the effect of radial play is almost eliminated. In this embodiment, since the magnet 110 has the chamfered portion 114, the change in the output of the magnetic sensor 120 is small even if the magnet 110 is displaced in the radial direction due to the radial play, so that the deviation from the output 231 having no play is sufficient. It can be made smaller.

As described above, in the magnet 110 according to the present embodiment, the chamfered portion 114 is provided by chamfering the corner close to the magnetic sensor 120 as in the first embodiment. As a result, as shown in Fig. 5, the influence of the radial play on the relationship between the rotation angle and the output of the magnetic sensor 120 is greatly reduced. Yes. In the above description, the magnetic sensor 120 has been described. However, even if the magnetic sensor 220 is V, the improvement effect as shown in FIG.

Next, the relationship between the size of the chamfered portion 114 and the rotation angle error will be described below.

As an example, Fig. 6 shows the results of evaluating the effect of the size of the chamfered portion 114 by simulation. Here, as shown in Fig. 6 (a), simulation is performed when the ratio of the chamfered area to the N or S pole cross-sectional area of the magnet 110 (hereinafter, the removal area and the height) is changed. It is carried out. In addition, the magnetic sensor 120 (and 220) is installed at a position below lm m in the lower right corner of the magnet 110. The magnetic sensor 120 (and 220) measures the magnetic flux in the vertical direction on the drawing.

In FIG. 6 (a), chamfering is performed as indicated by a broken line 241 parallel to the diagonal line of the cross-sectional area 240. At the position of magnetic sensor 120 (and 220) when the removal area is increased by 1/10 of the length of each side for two sides close to magnetic sensor 120 (and 220) with a cross-sectional area of 240 The magnetic flux density is shown in Fig. 6 (b). The horizontal axis indicates the distance that the magnet 110 moves in the radial direction.

[0044] In Fig. 6, the cross-sectional area 240 has a long side length of 5 mm and a short side length of 3 mm. The size of the chamfered part is 0.5mm for the long side up to 3.5mm, and 0.3mm for the short side up to 2.1mm. It is shown as ~ C3.5.

[0045] From FIG. 6 (b), it can be seen that the peak portion of the magnetic flux density becomes gentle as the chamfered portion is increased from C00 having no chamfered portion. That is, removal of the chamfered portion 114 It is shown that the change with respect to the radial movement of the magnet 110 decreases as the area increases. Since the peak value decreases as the peak portion of the magnetic flux density becomes gentle, the amplification factor of the amplifier 123 needs to be increased.

[0046] FIG. 7A shows the relationship between the size of the removal area of the chamfered portion 114 and the error of the calculated rotation angle measured using the magnetic sensors 120 and 220 in the above simulation. Fig. 7 (b) shows the relationship between the size of the removal area and the magnetic flux density at the positions of the magnetic sensors 120 and 220. From FIG. 7 (a), it can be seen that the rotation angle error decreases as the removal area of the chamfered portion 114 is increased. However, the size of the removal area in the figure C2. 5 that force ^s I force error even by increasing the most small tool more removal area error is not reduced when the, Ru.

[0047] The relationship between the size of the removal area of the chamfer 114 shown in FIG. 7 (b) and the magnetic flux density indicates that the magnetic flux density decreases with increasing removal area! Being! / This figure shows the maximum magnetic flux density and the average magnetic flux density when the moving distance due to radial play is changed. The maximum magnetic flux density approaches the average magnetic flux density as the removal area is increased. This is because the peak of the magnetic flux density decreases as shown in Fig. 6 (b).

[0048] As described above, since the magnetic flux density decreases as the removal area of the chamfered portion 114 is increased, it is necessary to increase the amplification magnification of the amplifier 123 accordingly. FIG. 8 shows the relationship between the size of the removal area, the amplification magnification of the amplifier 123, and the angle error. In the figure, the horizontal axis indicates the removal area to be chamfered as a percentage (%) of the total cross-sectional area (area of C00 without chamfered portion). As the removal area to be chamfered increases, it is necessary to increase the amplification factor of the amplifier 123 as shown in graph 251, and when the amplification factor is set in this way, the measurement error of the rotation angle is Like 252.

From FIG. 8, it can be seen that when the removal area of the chamfered portion 114 is about 25%, the angular error becomes the smallest. The removal area of the chamfered portion 114 should be 5 to 35% of the cross-sectional area of the N pole (and S pole) before chamfering, more preferably 20 to 30%. The chamfered shape preferably has a substantially rectangular cross section of the magnet.

As shown in FIG. 8, the rotation angle detection of the present embodiment including the magnetic sensors 120 and 220 In the apparatus 200, when the removal area of the chamfered portion 114 is, for example, 25% in terms of the cross-sectional area ratio, the measurement error of the rotation angle of the magnet 110 can be reduced to 0.3 degrees or less. When there is no chamfered portion, the error was about 1 degree, but it can be seen that the measurement accuracy can be greatly improved by providing the chamfered portion 114. In this embodiment, two magnetic sensors are used. However, the present invention is not limited to this. For example, three or more magnetic sensors can be used.

[0051] A rotation angle detection apparatus according to a third embodiment of the present invention will be described with reference to FIG. FIG. 9 is a structural diagram showing the rotation angle detection device 300 of the present embodiment, where (a) is a plan view in a direction perpendicular to the rotation axis, and (b) is a cross-sectional view as seen in a plane passing through the rotation axis. It is. The magnet 310 of the present embodiment is formed only on the peripheral portion excluding the central portion including the rotation axis.

[0052] As described above, when the magnet 310 is formed only on the peripheral portion, the size of the chamfered portion 314 is increased at a suitable ratio with respect to the cross-sectional area 315 of the magnet 310 before chamfering shown in Fig. 9 (b). It is good to decide the length. As in the second embodiment, the preferred size of the chamfered portion 314 is 5 to 35% of the cross-sectional area 315, more preferably 20 to 30%.

[0053] As in the case of the rotation angle detection device 300 of the present embodiment, even when the magnet 310 fixed to the rotating body is provided only at the peripheral portion to reduce the size of the magnet, the chamfered portion 314 is provided as described above. By providing it suitably, the rotation angle of the magnet 310 can be measured with high accuracy.

[0054] In the present invention, the magnet is preferably a magnet having at least a substantially circular outer periphery and a magnetic strength of the magnet that fluctuates along a circumferential direction of the magnet.

It should be noted that the description in the present embodiment shows an example of the rotation angle detection device according to the present invention, and is not limited to this. The detailed configuration and detailed operation of the rotation angle detection device in the present embodiment can be appropriately changed without departing from the spirit of the present invention.

Claims

The scope of the claims

[1] A magnet having at least an upper surface, a lower surface, and an outer peripheral surface, fixed to the detected rotating body and rotating integrally, and an outer peripheral corner formed by the upper or lower surface of the magnet and the outer peripheral surface. A rotation angle detection device comprising: a magnetic detector that is arranged to detect the magnetic strength of the magnet; and an arithmetic processing unit that calculates a rotation angle of the detected rotating body from an output of the magnetic detector. There,

A partial force formed by removing a part of the outer peripheral corner portion over the entire circumference forms a communication surface that connects the upper surface or the lower surface and the outer peripheral surface, and the magnetic detector is disposed in proximity to the communication surface. An apparatus for detecting a rotation angle.

[2] The outer peripheral surface is parallel to the rotation axis of the magnet, the outer peripheral surface is substantially perpendicular to the upper surface and the lower surface, and in the cross section passing through the rotation axis of the magnet, The upper surface line and the lower surface line corresponding to the lower surface and the lower surface line are substantially vertical, and the communication line corresponding to the communication surface communicates the outer peripheral line and the upper surface line or the lower surface line! / The rotation angle detection device described.

[3] The rotation angle detection device according to [1] or [2], wherein the connecting surface is a flat surface, a curved surface, or a multistage surface.

4. The magnetic detector according to claim 1, wherein a detection surface faces the communication surface and is arranged perpendicular to the rotation axis, and detects the magnetic strength in the rotation axis direction of the magnet. Any one of 3 to 3. The rotation angle detection device according to 1 above.

[5] The rotating shaft side end of the detection surface of the magnetic detector is disposed so as to be positioned between one end and the other end of the connecting surface. Item 5. The rotation angle detection device according to any one of Items 1 to 4.

[6] The ratio of the area of a part of the removed outer peripheral corner portion to the rectangular area formed by the outer peripheral line, the upper surface line, and the lower surface line of the cross section of the magnet passing through the rotating shaft is 5% or more. 6. The rotational angle detection device according to claim 1, wherein the force is 35% or less.

[7] The ratio of the area of a part of the removed outer peripheral corner portion to the rectangular area formed by the outer peripheral line, the upper surface line, and the lower surface line of the magnet passing through the rotation axis is 20% or more 30 The rotation angle detection device according to claim 6, wherein the rotation angle detection device is equal to or less than%.

The force according to any one of claims 1 to 7, wherein the magnet has at least an outer periphery that is substantially circular, and the magnet has a magnetic strength that varies along a circumferential direction of the magnet. A rotation angle detection device according to claim 1.